The invention relates generally to an OS/390 virtual machine. More particularly, the invention relates to a virtual machine allowing fast migration of the applications from any operating system to OS/390.
Computer operating systems and independent computer systems or applications (stand-alone programs) are the two main kinds of software products essential for information technology. In the past, with some hardware platforms, if a user needed to use different operating systems and/or independent programs, it was necessary to run them either on different computers or on the same computer one after another, which required shutting down the previous program before loading the subsequent one. An example of such computer architecture was the development of IBM 360-370.
One example of a situation requiring the ability to execute two operating systems of different types or versions simultaneously arises during a migration from an old operating system to a new one. This ability is also needed when one consolidates in one computer center a number of operations previously carried out in separate computer centers with different equipment.
In the past the disadvantage of having to use numerous computers for simultaneously running various operating systems and/or stand alone programs has been dealt with in two ways:
by using special operating systems, such as, for example, IBM""s VM operating system, allowing execution of other operating systems as its own tasks; and
by logical partitioning (LPAR), which allowed independent execution of different operating systems or stand alone programs on one computer (such as, for example, IBM""s LPAR in the 390 architecture).
Although both solutions make it possible to run various operating systems and/or independent programs on one computer, such approaches have a number of drawbacks.
In case of a VM operating system, instead of using additional computers it becomes necessary to use an additional operating system. In other words, one additional resource (extra computers) is substituted by another additional resource (operating system). The VM approach merely substitutes one problem for anotherxe2x80x94while it saves the use of additional computers, it requires the use of an additional operating system. An illustration of this drawback is the process of migration from an old operating system to a new one using a VM. Instead of using two (new and old) operating systems, the third operating system (VM) becomes involved, which increases costs, requires extensive personnel training and adds to resource requirements.
In case of logical partitioning, there exist the following three drawbacks:
1. A computer can be partitioned into only a limited number of LPARs (15 for IBM 390). However, it is often desirable to be able to execute more different operating systems and/or stand alone programs on one computer, in which case 15 LPARs is simply not enough.
2. Limited access from one operating system to the capabilities of another operating system or stand alone program running simultaneously on the same machine. For example, since LPAR 390 was specifically designed for separating different processes, interaction of operating systems running in different LPARs is basically similar to interaction of operating systems on separate computers.
3. Transition from dynamic resource allocation in case of one operating system to static resource allocation in LPAR, resulting in a loss of the possibility to reallocate available resources during execution. Such a loss results in insufficient exploitation of existing resources and capabilities or in the need to buy additional resources.
It is, therefore, desirable to have a system and method for a fast and efficient migration of the applications from any operating system to OS/390. Thus, there is a need in the art to develop a program and method for executing different operating systems and/or stand alone programs on one machine without using special operating systems or without having to use partitioning.
The present invention overcomes the drawbacks and disadvantages existing in the art by enabling the execution of any non-OS/390 operating system and its applications as a guest task in the OS/390 environment. Such execution is accomplished by creation of an interpretive spacexe2x80x94a virtual storage area of the OS/390 address space used by the present invention in interpretive execution mode of ESA/390.
It is, therefore, an object of the present invention to allow users to execute simultaneously on one computer various operating systems and applications (collectively called xe2x80x9cguestsxe2x80x9d) without having to use special operating systems, such as VM, but using an operating system already existing in a computer (such as OS/390 or VSE).
It is another object of the present invention to allow a more flexible resource allocation for guest execution than that of LPAR or VM.
Yet another object of the present invention is to enable guest execution of either IBM or non-IBM 370-390 operating systems in OS/390-VSE on the computers implementing S/390 principles of operation. Among these are all IBM 9672, multipurpose 2000, P/390, R/390 computers.
It is also an object of the present invention to provide for such execution of any guest system on the S/390 platform, which will not require any changes in a host system and in a guest system of any vendor.
It is also an object of the present invention to provide for fast and seamless transition of an application running on any operating system to OS/390, consolidation process based on one machine without LPARs under OS/390 with dynamic resource allocation.
It is yet another object of the present invention to give access to OS/390 system facilities to applications normally executed in other operating systems, such as S/370, and to reduce the average system reaction time on the same equipment (reduction of start-stop time for task execution by transferring I/O from 370 to 390).
In OS/390 address space controlled by the present invention, the OS/390 operating service is replaced by an operating service required by various application programs. Several OS/390 regions can be used by the present invention to run different applications in their own operating environment simultaneously. Running non-OS/390 applications in OS/390 address spaces, controlled by the present invention, lets OS/390 users work with those applications and their operational environment while sharing the OS/390 system resources with other users.
Functionally, the present invention is an OS/390 task, which allows it to use OS/390 capabilities unavailable in VM and LPAR. For example, DPPX and VSE IBM operating systems being executed in the interpretive space provided by the present invention can use virtual FBA (Fixed Block Architecture) disks located on VSAM (Virtual Sequential Access Method) files. Since VSAM files are visible for OS/390, OS/390 technologies can be used for DPPX and VSE disk images and DPPX and VSE files, which is impossible in other cases. Another example is a virtual inernetworking capability between guest systems being executed in OS/390. For instance, various DPPX or VSE guests executed in the interpretive space of the present invention can interact with each other via virtual TRN (Token Ring) without exiting to the physical network.
Compared to LPAR, the number of guest systems executed with the help of the interpretive space of the present invention is not limited to ten per one machine. Dynamic resource allocation is more efficient among OS/390 tasks (guest systems under ISX) than between LPARs. DPPX and VSE operating systems together with their applications become executable in OS/390 SYSPLEX (a multi-computer complex).
Compared to VM, ISX""s requirements for various resources, including maintenace, are very insignificant. ISX needs several segments of the main storage and several volume tracks.
The execution of applications with their own operational services is essentially simplified due to OS/390 resource allocation and control facilities, and the device emulation facilities provided by the present invention. Implementation of the present invention takes full advantage of the ESA/390 Interpretive Execution Mode.
Any operating system (except VM/ESA) together with applications could be executed in the virtual machine created by the present invention. At the same time it is possible to start some independent virtual machines in OS/390, in which different operating systems (for instance, DPPX, VSE) could be executed as OS/390 tasks. Therefore, the OS/390 functionality becomes accessible for other systems. The present invention provides virtual facilities for disks, networks and terminals, creating a possibility to transfer the processing to other geographical locations (transferability/mobility).
The present invention is used to achieve fast and inexpensive outsourcing, such as guest executing of non-OS/390 operating systems and tasks in OS/390, consolidation of various information technologies on OS/390 (for example, transfer of DPPX, VSE, MVS execution to OS/390), fast migration to OS/390, resulting in consolidation of computing equipment.
These and other advantages of the present invention will be more readily apparent from the detailed description of the invention and the accompanying drawings.